I don't really remember much about that, between 2-3 months I think. I always hit lv 120++ boss so I can gather loads of bond crystals from equip synthesis. Normally it's easy to get 5000 bond crystal->10 dancho medals in a month as long as you keep finding the bosses.
I used to have 200k mid equip seeds before danchou medals got introduced, now only 50k. Starting to worry if I can get 15000 bond crystal/month, considering I have to use bond crystal for 2nd aff items too.